Physical Science Objectives
Benchmark: Classify and compare substances on the basis of characteristic physical properties that can be demonstrated or
measured; for example, density, thermal or electrical conductivity, solubility, magnetic properties, melting and boiling
points, and know that these properties are independent of the amount of sample.
Notes:
Physical Properties – properties of a substance that can be observed or measured without changing the substances identity (in
other words without reacting it with another chemical and seeing what happens)
Thermal Conductivity – the ability to conduct heat; metals are good conductors nonmetals aren’t
Electrical Conductivity – the ability to conduct electricity; metals are good conductors nonmetals aren’t
Solubility – the ability of a substance to dissolve in another substance (example salt is soluble in water); if a substance dissolves
in another is soluble
-
Solvent – the “thing” that is doing the dissolving
Solute – the “thing” that is dissolved
Saturated Solution – No more can be dissolved
Magnetic Properties – caused by atoms all pointing in a certain direction
Melting Point – Point at which something turns from a solid to a liquid; (ice to water) – requires thermal (kinetic) energy to be
added; particles moving faster
Boiling Point – Point at which something turns from a liquid to a gas; (water to steam) – requires thermal (kinetic energy to be
added ; particles moving faster
Density – how tightly packed matter is; mass per unit volume. Density = Mass divided by volume
-
Something that is more dense that water sinks in water, something less dense than water floats in water
If it is a liquid density problem liquids with higher density will sink and be the bottom layer, the least dense liquid will
float and be in the top layer
Mass – amount of matter; usually they will give you this value
Volume – amount of space something takes up; may have to read a graduated cylinder; may have to calculate using v= length x
width x height; may have two graduated cylinders volume before given volume after given, subtract the numbers and that is
the volume of the substance
All of the above are Size Independent Properties (It does not matter how much of the samples you have; these properties will
always be the same)
Benchmark: Recognize that there are a finite number of elements and that their atoms combine in a multitude of ways to
produce compounds that make up all of living and nonliving things we encounter.
Elements – There are 92 naturally occurring elements that make up everything in the universe; these are the simple substance
made up of only 1 kind of atom; Examples include (carbon, oxygen, nitrogen, gold, silver, hydrogen, helium, calcium, etc.)
Elements are combined to make up everything else. Two or more elements combining is a compound.
Benchmark: Explore the scientific theory of atoms by using models to explain the motion of particles in solids, liquids, and
gases.
Matter Dance!!!
Solids – Particles closest together; least amount of energy;
Liquids – Particles father apart; more energy
Gases – Particles farthest apart; most energy
Benchmark: Recognize that elements are grouped in the periodic table according to similarities of their properties.
Groups – Up and Down Columns; Items in the same group have same chemical properties; examples Alkali Metals - Lithium (Li)
and Sodium (Na) are both reactive in water; Noble Gases -Neon and Argon are both non-reactive gases
Periods – Side to Side rows – Have the same number of energy levels
Left Side of Periodic Table – Mostly Metals which are shiny, good conductors of heat and electricity, malleable
Right Side of Periodic Table – Nonmetals which are dull, not good conductors, and are brittle
Benchmark: Explore the Scientific Theory of Atoms by recognizing that atoms are the smallest unit of an element and are
composed of sub-atomic particles.
Nucleus – Center of an Atom – contains Protons (Positive Charge) and Neutrons (Neutral Charge); most (99.9999%) is
contained here
Electron cloud – electrons spinning around the nucleus at nearly the speed of light
Atomic Number = Proton Number
Proton Number = Electron Number in Stable Atoms
Neutron = Atomic Mass – Atomic Number
Benchmark: Identify basic examples of and compare and classify the properties of compounds including acids, bases, and salts.
Compound – two or more chemical elements combined
Acids – compounds that produce Hydrogen ions in water; taste sour, ph 1-6; example Hydrochloric Acid, Citric Acid
Bases – compounds that produce Hydroxide ions in water ;taste bitter, ph 8-14; examples Sodium Hydroxide, Bleach, Soap
Salts – formed when an acid and a base combine; are neutral (non-reactive); Example NaCl (Table Salt)
Benchmark: Distinguish between mixtures and pure substances.
Pure Substances – Made of a single kind of atom (element) or molecule; Examples: Gold (single kind of atom), Silver (single
kind of atom), Water (single kind of molecule – only H2O), Salt (single kind of molecule – only NaCl)
Mixtures – made of two or more substances combined; Examples: Salt Water (salt and water); spaghetti; soup; air (made up
Nitrogen, Oxygen, and Carbon Dioxide Gases)
Benchmark: Differentiate between chemical changes and physical changes.
Physical Changes – only change the shape, size, state of matter, or where it is located; can be reversed more easily
Examples: Breaking Chalk (change in shape and size), Ripping Paper; Dissolving Salt in Water (the salt is still there only it
changes where it is located); melting ice, boiling water
Chemical Changes – changes the kind and arrangement of atoms that a substance is made of; can’t be as easily undone
Examples: burning wood; reacting something with an acid; baking soda and vinegar
Law of Conservation of Mass: Matter cannot be created or destroyed but only changed from one form to another
Translation: You don’t lose atoms in a chemical reaction they just get rearranged to form something else (even if something is
being burned)
Temperature Increases cause the rate of a chemical reaction to increase because the molecules are crashing into each other at
a faster rate.
Benchmark: Illustrate that the sun’s energy arrives as radiation with a wide range of wavelengths, including infrared, visible,
and ultraviolet, and that white light is made up of a spectrum of many different colors.
The sun gives off electromagnetic waves that can travel through a vacuum. They DO not need a substance (medium) to travel.
Electromagnetic waves are given off because of nuclear fusion reactions in the sun.
All electromagnetic waves are basically the same thing as visible light but they carry different amounts of energy because they
have different wavelengths and different frequencies.
Order of wavelength from largest to smallest is: Radio, Micro, Infrared, Visible, UltraViolet, X-Ray, Gamma.
Order of frequency from Lowest to Highest: Radio, Micro, Infrared, Visible, UltraViolet, X-Ray, Gamma
Order of Energy from Lowest to Highest: Radio, Micro, Infrared, Visible, Ultraviolet, X-Ray, Gamma.
Visible light that comes from the sun is White Light. It is actually made of the colors ROYGBIV. The color of light that you see on
an object is the color light reflected by the object, the rest is absorbed.
There are satellites that pick up all of these wavelengths and give us different types of information stars, planets, etc.
Benchmark: Recognize that light waves, sound waves, and other waves move at different speeds in different materials.
Observe and explain that light can be reflected, refracted, and/or absorbed.
Light travels fastest in a vacuum (empty space) if it goes into a different substance it slows down and can be refracted,
reflected, or absorbed. Light does NOT need a medium (substance) to travel through.
Light travels through materials in fastest in a vacuum, next fastest in a gas, then a liquid, and then a solid.
When a light wave goes from air to water for example it is bent, this is called refraction. This is because the light wave slows
down (slightly) and is bent. This is also how lenses work (air to glass).
When a light wave strikes a surface and bounces off this is called reflection. This is how you see objects and how a mirror
works.
Sound waves, Earthquake Waves, and Water Waves are mechanical waves and they need a medium (a substance to travel
through).
Mechanical waves travel slowest in gases (particles farthest apart), faster in liquids, and fastest in solids (particles closest
together).
Earthquake waves are how we can tell what the layers of the Earth are made of due to the bending of waves as they change
speed from a solid of one density to another.
Benchmark: Investigate and describe the transformation of energy form one form to another and the law of conservation of
energy.
CEMENT = Different Types of Energy
Chemical Energy - stored energy found in the bonds between atoms
Electrical Energy – when electrons move along a wire
Mechanical Energy – energy that an object has because it has moving parts (practically the same thing as kinetic)
Electromagnetic – energy in in the form of an electromagnetic wave radio, micro, infrared (heat), visible light, ultraviolet light,
x-ray, and gamma
Nuclear – Nuclear reactions from the sun or in a Nuclear Reactor
Thermal – Another name for heat caused by an increased motion of particles
Law of Conservation of Energy – Energy cannot be created or destroyed only changed from one form to another.
Examples: Flashlight – Chemical to electrical to Electromagnetic, Ipod – Chemical to electrical to electromagnetic and sound,
Wind Turbine – Mechanical to Electrical, Electric Engine (Chevy Volt) – Electrical to Mechanical
All Energy conversions are not 100% efficient and some energy can be lost as thermal (heat). It is “waste” energy.
Potential Energy = Stored Energy
Kinetic Energy = Movement
Holding something up in a high tower has potential. When you drop it and is falling it has kinetic (its moving). When it stops
again on the ground it has neither.
Kinetic Energy can be changed into potential Energy. For example – Wind moving a wind turbine spins a generator which
creates electricity which can be stored in a battery. Generators convert Mechanical Energy into Electrical Energy by moving a
wire through a magnetic field that causes electrons to flow). Engines convert Electrical or Chemical Potential Energy into
Kinetic Energy.
Benchmark: Observe and describe how heat flows in particular ways, moving from warmer objects to color ones until they
reach the same temperature AND that adding or removing heat can the state of an object.
Heat flows from warmer objects to colder objects (NOT THE OTHER WAY AROUND). Refrigerators and Air conditioners and Ice
cool things by removing or absorbing the heat (taking away the heat).
Your hand doesn’t cool down the stove/oven when you put it on, the heat gets transferred into your hand.
Conduction – transfer of heat from one object to another by direct contact
Convection – transfer of heat by moving fluids (air or water or rock); Hot air, water, or rock rises and cold air, water, or rock
sinks (convections in air currents cause breezes and wind, convections in water causes currents, convections in rock cause
currents in mantle that cause continental and oceanic crust to move).
Radiation – Transfer of heat through infrared waves
Add heat to solid change to liquid, etc. Heat causes changes.
Benchmark: Investigate and describe types of forces including contact forces and forces acting at a distance, such as electrical,
magnetic, and gravitational. Explore the law of gravity and tell the difference between weight and mass.
A force is a push or a pull acting on an object.
Contact Forces are those that require the two objects to be in physical contact.
Applied Force is a direct push or pull acting on an object.
Friction is a force that opposes the motion of objects as they slide or roll past one another.
Normal Force is a force that supports objects in an upward direction (ground pushing on table)
Tensional Force is in a rope or wire.
Spring Force is in a compressed or stretched spring (duh)
Action at a Distance Forces are those that require no physical contact between the two objects.
Gravity is the force of attraction between any two objects because of their masses.
Static Electricity is a force of attraction caused by a build up of electrical charges on one object creating a slightly
positive or negative side.
Magnetism is a force that exists because of the alignment of atoms in a certain direction.
Newton’s law of gravity states that the force of attraction between two objects increases when the objects are more massive
and when objects are closer together. The more massive and the closer they are there is more gravity.
Weight is a measure of the force of attraction between two objects and can change on different planets with different
amounts of gravity.
Mass is the amount of matter in an object and does not change if gravity changes.
Benchmark: Investigate and describe that an unbalanced force acting on an object changes its speed, or direction of motion, or
both. Measure and graph distance versus time for an object moving at a constant speed.
When forces are balanced things don’t move!
When force are unbalanced things move!
When forces are going in the same direction they add together.
When forces are going in opposite directions they subtract from one another.
Force = Mass X Acceleration
Speed = Distance divide by time
Acceleration = Change in Velocity divided by time it takes to change it
Positive Acceleration = Objects are Speeding up
Negative Acceleration = Objects are Slowing Down
Speed Vs. Time Graph